| Due to the imperfect processing technology system of beef meatballs,the quality of beef meatballs produced by different manufacturers is uneven,resulting in poor water-holding capacity and loose texture of traditional beef meatballs in China,which restricts the industrial development of beef meatballs.Studies have shown that oat dietary fiber(ODF)can be used as a thickener to improve the structural characteristics and gel properties of meat products.The mechanical effect of ultrasound can inhibit protein aggregation,change protein structure,improve the gel properties of myofibrillar protein(MP),and ensure product quality.Therefore,exploring the study on the mechanism and application of improving beef MP gel properties by ultrasonic combined with ODF has practical guiding significance for solving the problems existing in traditional beef meatballs.In the paper,the effect mechanism of ultrasonic combined with ODF on the gel properties of MP and the processing quality and freezing stability of beef meatballs were systematically explored,thereby providing a theoretical basis for the development of high-quality beef meatballs.Firstly,the effects of ultrasonic power and ODF addition on the texture,water-holding capacity and microstructure of beef MP gel were investigated by taking MP as the research object.The results showed that the MP gel texture characteristics and water-holding capacity were the best,and the gel network structure was more compact when the ultrasonic power was 80 W and 120 W,respectively,and the amount of ODF added was 3%.Secondly,the improvement mechanism of ultrasonic(80 W,120 W)combined with 3%ODF on the gel properties of beef MP was investigated by comparing the control group,the ultrasonic group and the ODF group.The results showed that the U120+ODF group(120 W ultrasonic power combined with 3%ODF)had the best gel hardness,chewiness and three-dimensional network structure,indicating that ultrasound and ODF had a synergistic effect.In addition,ultrasonic combined with ODF can promote the degradation of myosin,thereby increasing the solubility of MP.Compared with U80 and U120 groups,the β-sheet content of U80+ODF group(80 W ultrasonic power combined with 3%ODF)and U120+ODF group was as high as 46%and 40%,respectively.At the same time,compared with the ultrasonic group alone,the ODF group alone had a stronger effect on improving the gel properties of MP.In summary,the U120+ODF group had the best MP gel properties.Considering the advantages of ODF in improving the gel properties of MP,the third chapter explored the effect of ultrasonic(120 W)combined with different ODF additions on the processing quality of beef meatballs.Furthermore,compared with traditional beef meatballs,the quality characteristics,volatile flavor substances and their precursors of beef meatballs treated with ultrasonic(120 W)combined with ODF(1%,2%,3%,4%and 5%)were investigated.The results showed that beef meatballs treated by ultrasonic combined with ODF had better edible properties.When the addition amount was 3%,the beef meatballs had the best elasticity,chewiness,moderate hardness,and a more regular and uniform network structure was formed inside the sample.The production rate of the UODF-3 group(ultrasonic combined with 3%ODF group)was significantly higher than the CG group(traditional group)(P<0.05).Ultrasonic combined with ODF effectively improved the water and oil retention and surface L*value of beef meatballs.In addition,66 aroma components of beef meatballs were screened by odour activity value(OAV)method.Among them,n-nonanal,n-hexanal and n-pentanol were the key main flavor components(OAV≥1.00)in each treatment group.Ultrasonic combined with ODF could promote the formation of free fatty acids and essential amino acids in beef meatballs.From the content and composition of free fatty acid and essential amino acid,the UODF-2 group(ultrasonic combined with 2%ODF)and the UODF-3 group had better edible value and flavor quality.The precursors with strong correlation with volatile flavor compounds were screened by partial least squares regression(PLSR).Among them,phenylalanine and phenylacetaldehyde had a strong correlation,and 3-methylbutyraldehyde had a strong correlation with palmitoleic acid.In summary,the processing quality of beef meatballs prepared by UODF-3 group was the best.Finally,the effect of ultrasonic combined with ODF on the quality stability of beef meatballs during frozen storage was investigated.The results showed that ultrasonic combined with ODF could significantly improve the sensory characteristics and texture of beef meatballs.When stored for 120 days,the sensory characteristics of beef meatballs were still acceptable.Meanwhile,the a*value on the surface of beef meatballs significantly decreased with the prolongation of freezing storage time(P<0.05),indicating that the degree of oxidation of beef meatballs increased with the prolongation of frozen storage time.The water loss rate,freezable water content,thiobarbituric acid value(TBARs),and total volatile basic nitrogen(TVB-N)values showed an overall upward trend with the prolongation of storage time.In addition,the frozen water content of the ultrasonic combined with ODF group was significantly lower than that of the control group(P<0.05),indicating that ultrasonic combined with ODF could inhibit the growth of ice crystals to a certain extent.The microstructure results further confirmed that ultrasonic combined with ODF contributed to beef meatballs forming a denser and more uniform microstructure and reduced the damage to the internal structure of beef meatballs during freezing.In summary,ultrasonic combined with ODF could effectively reduce the quality changes of beef meatballs during frozen storage. |
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